Mass renaming app?

[HarryTrotter]

Anyone knows a program that could help?Basically,I have to add an extension in the name of a whole bunch of files.For example,everything should be formatted as file name.full . Now adding the .full part to everything is a bit of a problem.

[Tomato]

https://www.advancedrenamer.com/download -This is what I use. Comes in very handy for a lot of things.

[HarryTrotter]

Cheers,mate.
That saved me a lot of  time.